Incidence, Risk Factors and Outcomes of SARS-CoV-2 Infection in Pregnant Women: The COROPREG Population-Based Study

Abstract

Background: Population-based data are needed to reliably assess the impact of SARS-CoV-2 infection during pregnancy.

Objectives: To estimate the population-based incidence of SARS-CoV-2 infection and its severe forms in the obstetric population, identify risk factors of severe SARS-CoV-2 infection (severe COVID-19) and describe delivery, maternal and neonatal outcomes by disease severity, using a definition of severity based on organ dysfunction.

Methods: A prospective population-based study conducted over the three first pandemic waves between March 2020 and April 2021 in 281 maternity hospitals in six French regions included all women with SARS-CoV-2 infection during pregnancy or within 7 days post-partum, whether symptomatic or not, hospitalised or not. Severe COVID-19 forms were defined a priori using clinical, biological and management criteria of organ dysfunction. We calculated infection and severe infection rates and studied associations between sociodemographic, medical and pregnancy characteristics and severe COVID-19 by univariate and multivariate modified Poisson regression modelling.

Results: From a population of 385,214 deliveries in the participating regions, 6015 women with SARS-CoV-2 infection were identified, including 337 severe cases. The rates of severe COVID-19 were 1.1, 0.9 and 3.6 per 1000 deliveries during the first, second and third pandemic waves, respectively, and the proportions of severe COVID-19 were 8.6%, 3.4% and 9.3%, respectively. On multivariate analysis, the risk of severe COVID-19 was associated with younger and older age, migrant status, living with > 4 people, overweight or obesity, chronic hypertension or diabetes and infection ≥ 22 weeks of gestation rather than earlier in pregnancy. Neonatal morbidity occurred mostly with severe maternal infection.

Conclusion: Using an organ-based definition of severity and population-based data, rates of severe COVID-19 appeared lower than in previous studies. A permanent perinatal surveillance system is needed to assess efficiently and rapidly the impact of future pandemics.

Keywords: COVID‐19; SARS‐CoV‐2; maternal morbidity; neonatal morbidity; pregnancy; risk factors.

FIGURE 1

Public health and government measures in France according to the COROPREG study periods.

FIGURE 2

Rates of hospitalisation (green), severe COVID‐19^* (blue) and intensive care unit admission (yellow) with obstetric SARS‐CoV‐2 infection, by 1000 deliveries (lines) and by 100 infected women (bars), by study period. ^*Severe infection was defined by at least one of arterial pH < 7.38, lactate level > 2.0 mmol/L, PaO₂ ≤ 80 mmHg, PaO₂/FIO₂ < 300, continuous positive airway pressure, high‐flow oxygen therapy, invasive mechanical ventilation, clinical diagnosis of acute respiratory distress requiring oxygen therapy, prone position, extracorporeal membrane oxygenation, platelet count < 70,000/mm³, prothrombin time < 60%, plasmatic fibrinogen level < 2 g/L, creatinine level ≥ 110 μmol/L, dialysis, catecholamines administration.